Therapeutic agents

ABSTRACT

Therapeutic or preventive agents for diseases due to the action of aldose reductase; and aldose reductase inhibitors, characterized by containing at least one compound having an aldose reductase inhibiting activity which is selected from among 2,5-dihydroxytetra-hydro-2-furancarboxylic acid, derivatives of the same, optical isomers of both and pharmacologically acceptable salts of them.

This application is a 371 of PCT/JP99/03404, filed Jun. 25, 1999.

TECHNICAL FIELD

The present invention relates to a pharmaceutical composition or areagent having an aldose reductase inhibitory activity.

BACKGROUND ART

Aldose reductase (hereinafter referred to as AR) is an enzyme involvedin a polyol pathway, one of glucose-metabolic pathways, in a livingbody. The polyol pathway consists of two pathways, i.e., a pathway ofreducing glucose to sorbitol involving AR; and a pathway ofdehydrogenating sorbitol to D-fructose involving sorbitol dehydrogenase(hereinafter referred to as SDH). It is known that the polyol pathwayexists in a number of tissues including brain, liver, pancreas, kidney,adrenal gland, testis, seminal vesicle, placenta, erythrocytes, lens,retina and peripheral nerve. However, the physiological significance ofthe polyol pathway has been confirmed only in the seminal vesicle, inwhich it acts as a pathway for producing energy source for sperms. It isbelieved that, in other sugar-metabolic pathways in normal cells, mostof the glucose incorporated into a cell is converted into glucose6-phosphate by the action of hexokinase to be metabolized in aglycolytic pathway, while only several percents of the glucose ismetabolized through the polyol pathway [Tsuyoshi Tanimoto, Pharmacia,24:459-463 (1988)].

When influx of glucose into a cell increases, the glucose which theglycolytic pathway fails to process is brought to the polyol pathway.The SDH activity is lower than the AR activity. Therefore, anintermediary metabolite, sorbitol, is produced in large quantities ifthe influx of glucose continues. Sorbitol is highly polar and,therefore, does not efficiently diffuse outside the cell. Thus, sorbitolis accumulated with the cell, resulting in the increase in intracellularosmotic pressure [Tsuyoshi Tanimoto, Pharmacia, 24:459-463 (1988)].Examples of tissues in which glucose present in blood (blood sugar)unlimitedly flows into cells include insulin-independent tissues such ascentral nervous system, blood cells and medulla glandulae [MedicalDictionary, 17th edition, Nanzando, Co. Ltd. (1990)].

Diseases due to the accumulation of sorbitol have been reported. Forexample, diabetic cataract has been reported to be caused as a result ofthe following steps: AR in lens of eyeballs converts glucose andgalactose into corresponding sugar alcohols. The sugar alcohols areinappropriately accumulated in the lens to increase the osmoticpressure. The increased osmotic pressure damages the lens to cause thecataract [see J. H. Kinoshita et al., Biochimica et Biophysica Acta,158:472 (1968) and references cited therein]. Various harmful influencesdue to accumulation of sorbitol in lens, peripheral nerve cord andkidney in a diabetic animal have also been reported [see A. Pirie etal., Experimental Eye Research, 3:124 (1964); L. T. Chylack Jr. et al.,Investigative Ophthalmology, 8:401 (1969); and J. D. Ward et al.,Diabetologia, 6:531 (1970)].

Among complications of diabetes in which blood sugar value is elevated,AR is involved in, for example, cataract, retinopathy, peripheralneuropathy and/or nephropathy. It is essential to inhibit the activityof AR, which is responsible for the above-mentioned complications, asstrongly as possible in order to prevent, ameliorate or treat them.

Other diabetic complications include, for example, infectious diseasesdue to decrease in phagocytosis in leukocytes and diabetic coma[Shin-ban Katei No Igaku, 11th edition, Jiji Press, Ltd. (1996)] andarteriosclerosis due to atheromatous degeneration in great vessel walls[Medical Dictionary, 17th edition, Nanzando, Co. Ltd. (1990)].

OBJECTS OF INVENTION

The main object of the present invention is to develop a compound havingan AR inhibitory activity and to provide a pharmaceutical compositionfor a disease due to AR or a composition for inhibiting AR whichcontains the compound as its active ingredient.

The other objects and advantages of the present invention will beapparent from the description below.

SUMMARY OF INVENTION

The present inventors demonstrated that2,5-dihydroxytetrahydro-2-furancarboxylic acid, as well as opticalisomers and salts thereof have carcinostatic activities (WO 98/32749).As a result of intensive studies, the present inventors have found thatthese compounds have highly selective ability of inhibiting an ARactivity. Thus, the present invention has been completed.

Thus, the first aspect of the present invention relates to apharmaceutical composition for treating or preventing a disease due toan AR activity, which contains at least one compound having an ARinhibitory activity selected from the group consisting of2,5-dihydroxytetrahydro-2-furancarboxylic acid of formula 1:

as well as derivatives, optical isomers and pharmacologically acceptablesalts thereof.

The second aspect of the present invention relates to a composition forinhibiting AR, which contains at least one compound having an aldosereductase inhibitory activity selected from the group consisting of2,5-dihydroxytetrahydro-2-furancarboxylic acid, as well as derivatives,optical isomers and salts thereof.

DETAILED DESCRIPTION OF THE INVENTION

2,5-Dihydroxytetrahydro-2-furancarboxylic acid is produced, for example,by heating glucaric acid.

Glucaric acid (also called as saccharic acid) is represented bymolecular formula C₆H₁₀O₈ (molecular weight 210.14). Glucaric acid is adicarboxylic acid produced by oxidizing D-glucose, or an oligosaccharideor a polysaccharide that contains D-glucose with nitric acid or thelike. It can also be produced by oxidizing D-glucuronic acid withbromine water.

For example, a reaction of glucaric acid at 121° C. for 4 hours resultsin a reaction mixture containing2,5-dihydroxytetrahydro-2-furancarboxylic acid.2,5-Dihydroxytetrahydro-2-furancarboxylic acid can be purified andisolated from the reaction product by subjecting it to reverse phasecolumn chromatography.

2,5-Dihydroxytetrahydro-2-furancarboxylic acid can also be produced byhydrating α-ketoglutarate semialdehyde. α-Ketoglutarate semialdehyde canbe produced according to a known method [Journal of Bacteriology,116:1364-1354 (1973)].

Any derivatives of 2,5-dihydroxytetrahydro-2-furancarboxylic acid may beused in the present invention as long as they have an AR inhibitoryactivity. Examples of the derivatives include, but are not limited to, acompound of formula 2:

wherein R¹, R² and R³ may be the same or may be different each other,and are hydrogen, an aliphatic group, an aromatic group or an aromaticaliphatic group; m and n are 1 or 0, provided that in case of m=n=0, R¹,R² and R³ are not simultaneously hydrogen.

Examples of aliphatic groups include linear alkyl groups of 1-30carbons, branched alkyl groups such as isopropyl group, isobutyl group,sec-butyl group, tertbutyl group, isopentyl group, neopentyl group andtertpentyl group, linear alkenyl groups such as etenyl group, allylgroup, trans-1-propenyl group, cis-1-propenyl group, cis-8-heptadecenylgroup, cis-8-cis-11-heptadecadienyl group,cis-8-cis-11-cis-14-heptadecatrienyl group,cis-5-cis-8-cis-11-heptadecatrienyl group,cis-4-cis-7-cis-10-nonadecatrienyl group,cis-4-cis-7-cis-10-cis-13-nonadecatetraenyl group,cis-4-cis-7-cis-10-cis-13-cis-16-nonadecaheptaenyl group,cis-12-henicosenyl group andcis-3-cis-6-cis-9-cis-12-cis-15-cis-18-henicohexaenyl group, as well asbranched alkenyl groups such as isopropenyl group,cis-1-methyl-1-propenyl group, trans-1-methyl-1-propenyl group,trans-1-methyl-1-propenyl group and trans-1-ethyl-1-propenyl group.

Examples of aromatic groups include phenyl group, naphthyl group,biphenyl group, pyrrolyl group, pyridyl group, indolyl group, imidazolylgroup, tolyl group, xylyl group, o-chlorophenyl group, o-bromophenylgroup, o-nitrophenyl group and o-methoxyphenyl group.

Examples of aromatic aliphatic groups include phenylalkyl groups of 1-15alkyl group carbons (e.g., benzyl group or phenetyl group), stylyl groupand cinnamyl group.

The compound of formula 2 can be produced by reacting2,5-dihydroxytetrahydro-2-furancarboxylic acid with an alcohol having analiphatic group, aromatic group or an aromatic aliphatic group and/or areactive derivative thereof (e.g., alkyl halide, aryl halide, acidester, diazo compound, salt and alkene produced by dehydrating alcohol),and/or by reacting 2,5-dihydroxytetrahydro-2-furancarboxylic acid with acarboxylic acid having an aliphatic group, aromatic group or an aromaticaliphatic group and/or a reactive derivative thereof (e.g., acid halide,acid anhydride, acid ester and salt).

After the thus produced derivative is purified, its AR inhibitoryactivity is measured. Then, the derivative can be used in the presentinvention. The degree of inhibition of alcohol dehydrogenase(hereinafter referred to as ADH) activity by the compound at aconcentration that results in 50% inhibition of the AR activity (IC₅₀)is 20% or less, preferably 15% or less, most preferably 10% or less.

Furthermore, 2,5-dihydroxytetrahydro-2-furancarboxylic acid orderivatives thereof purified as described above can be opticallyresolved to obtain 2,5-dihydroxytetrahydro-2-furancarboxylic acid orderivatives thereof in (−) and (+) form.

Optical isomers can be separated by mechanical resolution of racemicmixture, preferential crystallization, resolution by crystallizing as adiastereomeric salt or an inclusion compound, kinetic resolution usingan enzyme or a microorganism, chromatographic separation or the like.

Gas chromatography, liquid chromatography, thin-layer chromatography orthe like using an appropriate chiral stationary phase can be used forchromatographic resolution.

A method in which a chiral stationary phase is used, a method in which achiral eluent is used, separation as a diastereomer or the like can beused for optical resolution by liquid chromatography. An amide-typestationary phase, a urea-type stationary phase, a ligand exchange-typestationary phase, a polysaccharide or polysaccharide derivativestationary phase, a protein stationary phase, a polymethacrylate esterstationary phase, a polymethacrylamide stationary phase or the like canbe used as a chiral stationary phase. A hexan-type eluent, analcohol-type eluent, an aqueous (buffer) eluent or the like can beappropriately used as an eluent depending on the stationary phase used.

2,5-dihydroxytetrahydro-2-furancarboxylic acid has two asymmetriccarbons at 2-position and 5-position in its molecular structure. Thus,there exist four stereoisomers represented by (2S,5S), (2S,5R), (2R,5S)and (2R,5R) forms. As used herein,2,5-dihydroxytetrahydro-2-furancarboxylic acid and derivatives thereofinclude any stereoisomers without being limited to a specificconformation as long as they have an AR inhibitory activity.Furthermore, 2,5-dihydroxytetrahydro-2-furancarboxylic acid andderivatives thereof may be optical isomers or racemic modifications aslong as they have an AR inhibitory activity.

2,5-dihydroxytetrahydro-2-furancarboxylic acid has a low activity ofinhibiting ADH, which has substrate specificity similar to that of AR.The activities of inhibiting enzymes are highly selective for AR.

Use of esters of pharmaceuticals (e.g., penicillin and non-steroidalanti-inflammatory drug) which are hydrolyzed under physiologicalconditions as pharmaceuticals has become common. Thus, the activeingredient contained in the pharmaceutical composition for treatment orprevention of the present invention is not specifically limited to theabove-mentioned compounds having the AR inhibitory activity. Forexample, the active ingredient may be a compound that is hydrolyzedunder physiological conditions to generate the above-mentioned compoundhaving the AR inhibitory activity. That is, compounds having an ARinhibitory activity as used herein include so-called prodrug compounds,which themselves are inactive, but are converted to compounds having anAR inhibitory activity in vivo.

Examples of esters of 2,5-dihydroxytetrahydro-2-furancarboxylic acidthat are hydrolyzed under physiological conditions include a compound offormula 3:

wherein G₁ and G₂ are independently hydrogen or a group that forms acommonly used ester being able to be hydrolyzed under physiologicalconditions, provided that G₁ and G₂ are not simultaneously hydrogen.

The group that forms an ester to be used for G₁ can be appropriatelyselected from, for example, 1H-furan-5-on-1-yl,1H-isobenzofuran-3-on-1-yl, γ-butyrolacton-4-yl, —CH₂CH₂NR⁴R⁵,—CHR⁶OCOR⁷ or —CHR⁶OCOOR⁸, wherein R⁴ and R⁵ are independently (C1-C4)alkyl or R⁴ and R⁵ form pyrrolidine, piperidine or morpholine ringtogether with the nitrogen to which they are attached; R⁶ is hydrogen ormethyl; R⁷ is (C1-C6) alkyl, (C1-C6) carboxyalkyl, carboxycyclohexyl orcarboxyphenyl; and R⁸ is (C1-C6) alkyl. The group that forms an ester tobe used for G₂ can be appropriately selected from, for example, acylgroup and —PO(ONa)₂. Without limitation, acyl groups having a littlenumber of carbons are generally preferable. For example, formyl group,acetyl group and propionyl group are used. The above-mentioned compoundscan be prepared from 2,5-dihydroxytetrahydro-2-furancarboxylic acid oroptical isomers thereof according to known methods.

Examples of salts used in the present invention include alkaline metalsalts, alkaline earth metal salts and salts with organic bases.Pharmacologically acceptable salts mean salts of the above-mentionedcompounds having the AR inhibitory activity which are substantiallynon-toxic to organisms. Examples of pharmacologically acceptable saltsinclude sodium, potassium, calcium, magnesium, ammonium or protonatedsalts with benzathine(N,N′-di-benzylethylenediamine), choline,ethanolamine, diethanolamine, ethylenediamine,meglumine(N-methylglucamine), benethamine(N-benzylphenetylamine),piperazine or tromethamine(2-amino-2-hydroxymethyl-1,3-propanediol).These salts are obtained by converting a compound having an ARinhibitory activity selected from the group consisting of2,5-dihydroxytetrahydro-2-furancarboxylic acid, as well as derivativesand optical isomers thereof according to known methods.

The pharmaceutical composition for treating or preventing a disease dueto an AR activity, which contains at least one compound having an ARinhibitory activity selected from the group consisting of2,5-dihydroxytetrahydro-2-furancarboxylic acid, as well as derivatives,optical isomers and pharmacologically acceptable salts thereof as anactive ingredient of the first aspect of the present invention may beprepared by formulating at least one compound having an AR inhibitoryactivity selected from the group consisting of2,5-dihydroxytetrahydro-2-furancarboxylic acid, as well as derivatives,optical isomers and pharmacologically acceptable salts thereof as anactive ingredient with a known pharmaceutical carrier.

At least one compound having an AR inhibitory activity selected from thegroup consisting of 2,5-dihydroxytetrahydro-2-furancarboxylic acid, aswell as derivatives, optical isomers and pharmacologically acceptablesalts thereof is generally mixed with a pharmaceutically acceptableliquid or solid carrier and, optionally, solvent, dispersing agent,emulsifier, buffering agent, stabilizer, excipient, binder,disintegrant, lubricant and the like to formulate it. The formulationmay be in a form of a solid preparation such as tablet, granule, powder,epipastic and capsule, or a liquid preparation such as normal solution,suspension and emulsion. In addition, the composition may be formulatedinto a dried preparation, which can be reconstituted as a liquidpreparation by adding an appropriate carrier before use.

The pharmaceutical carrier can be selected according to theabove-mentioned particular administration route and dosage form. For anoral preparation, starch, lactose, sucrose, mannit,carboxymethylcellulose, cornstarch, inorganic salts and the like areutilized, for example. Binder, disintegrant, surfactant, lubricant,fluidity-promoting agent, tasting agent, coloring agent, flavoring agentand the like can also be included in oral preparations.

A parenteral preparation can be prepared according to conventionalmethods by dissolving or suspending at least one compound having an ARinhibitory activity selected from the group consisting of2,5-dihydroxytetrahydro-2-furancarboxylic acid, as well as derivatives,optical isomers and pharmacologically acceptable salts thereof, in adiluent. The diluents include injectable distilled water, physiologicalsaline, aqueous glucose solution, injectable vegetable oil, sesame oil,peanut oil, soybean oil, corn oil, propylene glycol and polyethyleneglycol. Optionally, sterilizer, stabilizer, osmotic regulator, smoothingagent and the like may be added to the solution or suspension.

The pharmaceutical composition for treating or preventing a disease dueto an AR activity of the present invention (hereinafter simply referredto as the pharmaceutical composition of the present invention) isadministered through a suitable route for the dosage form of thecomposition. The administration route is not limited to a specific one.The composition can be administered internally or externally (ortopically) or by injection. The injectable preparation can beadministrated intravenously, intramuscularly, subcutaneously,intradermally and the like, for example. External preparations include asuppository.

A dosage of the pharmaceutical composition of the present invention isappropriately determined and varies depending on the particular dosageform, administration route and purpose as well as age, weight andconditions of a patient to be treated. In general, a daily dosage for anadult person is 0.1 to 2000 mg/kg in terms of the amount of at least onecompound having an AR inhibitory activity selected from the groupconsisting of 2,5-dihydroxytetrahydro-2-furancarboxylic acid, as well asderivatives, optical isomers and pharmacologically acceptable saltsthereof contained in the formulation. Of course, the dosage can varydepending on various factors. Therefore, in some cases, a less dosagethan the above may be sufficient but, in other cases, a dosage more thanthe above may be required. The pharmaceutical composition of the presentinvention can be administrated orally as it is, or it can be taken dailyby adding to selected foods and drinks.

Since the pharmaceutical composition of the present invention has an ARinhibitory activity, it can be used for preventing and/or treating adisease due to an AR activity. Examples of the diseases due to an ARactivity include diabetic complications as described above.Specifically, such diseases include cataract, peripheral neuropathy,retinopathy and/or nephropathy. The pharmaceutical composition of thepresent invention can be used in order to prevent and/or treat suchdiseases.

A dosage of the pharmaceutical composition for preventing and/ortreating diabetic complications including cataract, peripheralneuropathy, retinopathy and/or nephropathy is appropriately determinedand varies depending on the particular dosage form, administration routeand purpose as well as age, weight and conditions of a patient to betreated. In general, a daily dosage for an adult person is 1 to 1000 mg,preferably 10 to 200 mg in terms of the amount of the active ingredientcontained in the formulation. Of course, the dosage can vary dependingon various factors. Therefore, in some cases, a less dosage than theabove may be sufficient but, in other cases, a dosage more than theabove may be required. The pharmaceutical composition of the presentinvention can be administrated orally as it is, or it can be taken dailyby adding to selected foods and drinks.

The pharmaceutical composition of the present invention may be used incombination with a substance having an AR inhibitory activity derivedfrom plants. Any plants may be used as long as they contain a substancehaving an AR inhibitory activity. Examples of the plants include, butare not limited to, those belonging to family Liliaceae. Examples of theplants belonging to family Liliaceae include onions (Allium cepa)belonging to genus Allium. A substance having an AR inhibitory activitycan be prepared from onions, for example, by extracting bulbs or bulbpellicles of onions with hot water. The extract having an AR inhibitoryactivity may be used in combination with the pharmaceutical compositionof the present invention. The onion extract having an AR inhibitoryactivity may be used alone.

The process for preparing a substance having an AR inhibitory activityfrom bulbs or bulb pellicles of onions is not limited to a specific one.For example, after bulb pellicles of onions are washed with water, wateris added thereto to adjust the content of pellicles to 0.1 to 20% byweight. The mixture is heated at 50 to 130° C. for several minutes toseveral hours. Thus, an extract containing a substance having an ARinhibitory activity at a high concentration can be obtained. The extractselectively inhibits AR. Therefore, the extract is used for a healthydrink useful for treating or preventing a disease due to an AR activity.Such a healthy drink may be produced by using an extract of bulbs and/orbulb pellicles of onions as an active ingredient according to aconventional method for producing drinks. Alternatively, flavonoidcompounds having an AR inhibitory activity such as spiraein, quercetin,quercitrin and myricetin may be concentrated from the extract for use asactive ingredients. In addition, the flavonoid compounds may be used incombination with the pharmaceutical composition of the presentinvention.

No toxicity is observed when a physiologically effective amount of acompound having an AR inhibitory activity selected from the groupconsisting of 2,5-dihydroxytetrahydro-2-furancarboxylic acid, as well asderivatives, optical isomers and pharmacologically acceptable saltsthereof used in the present invention was orally administered to amouse.

The composition for inhibiting AR of the second aspect of the presentinvention may be prepared by formulating at least one compound having anAR inhibitory activity selected from the group consisting of2,5-dihydroxytetrahydro-2-furancarboxylic acid, as well as derivatives,optical isomers and salts thereof into a conventional reagent formaccording to the method as described above with respect to theproduction of the pharmaceutical composition. The inhibitory compositionis useful for studying diseases involving AR and for screening ARinhibitors.

The following Examples further illustrate the present invention indetail but are not to be construed to limit the scope thereof. Percent(%) in Examples means percent by weight unless otherwise stated.

EXAMPLE 1

(1) D-saccharate 1,4-lactone-hydrate (Nacalai Tesque, 304-35) wasdissolved in 100 ml of water. The pH of the solution was 2.5. 30 ml ofthe resulting solution was then heated at 121° C. for 4 hours.

The heated solution was subjected to HPLC under the followingconditions. 2,5-dihydroxytetrahydro-2-furancarboxylic acid eluted infractions at 13.5 to 15 minutes was collected in large quantities, andconcentrated to dryness under reduced pressure.

Column: TSKgel ODS-8OTs (5 μm), 20 mm×25 cm;

Mobile Phase A: 0.1% aqueous trifluoroacetic acid solution;

Mobile Phase B: aqueous solution containing 0.1% trifluoroaceticacid/50% acetonitrile;

Flow rate: 8 ml/minute;

Elution: 100% Mobile Phase A (10 minutes)→from 100% Mobile Phase A to100% Mobile Phase B (40 minutes);

Detection: absorbance at 215 nm.

(2) Confirmation of AR inhibitory activity of2,5-dihydroxytetrahydro-2-furancarboxylic acid.

2,5-dihydroxytetrahydro-2-furancarboxylic acid was added to an ARreaction system to determine the AR inhibitory activity.

NADPH (Nacalai Tesque) as a hydrogen donor and methylglyoxal (NacalaiTesque) as a substrate for the enzyme were used. A commerciallyavailable enzyme solution (Wako Pure Chemical Industries, code012-13991) was diluted. for use as AR.

The AR activity was measured as follows.

40 μl of sterile pure water, 20 μl of 1 mM aqueous NADPH solution and 10μl of enzyme dilution were added to 100 μl of 200 mM phosphate buffer(pH 6.2). 10 μl of sterile pure water was further added to the mixture.After 20 μl of 100 mM aqueous methylglyoxal solution was added thereto,the change in absorbance at 340 nm was monitored at room temperature for3 minutes. The enzymatic activity was determined on the basis of thechange in absorbance per minute. Next, aqueous solution of2,5-dihydroxytetrahydro-2-furancarboxylic acid at a varyingconcentration was added to the reaction system as described above inplace of 10 μl of sterile pure water. The enzymatic activity was thendetermined as described above.

The AR inhibitory activity of 2,5-dihydroxytetrahydro-2-furancarboxylicacid was determined based on the enzymatic activity inhibition ratecalculated according to the following equation:

Enzymatic activity inhibition rate (%)={1-(enzymatic activity with theaddition of aqueous 2,5-dihydroxytetrahydro-2-furancarboxylic acidsolution)/(enzymatic activity with the addition of water)}×100.

If 2,5-dihydroxytetrahydro-2-furancarboxylic acid does not have an ARinhibitory activity, the enzymatic activity inhibition rate is 0%.

The activity inhibition rate on the AR activity of2,5-dihydroxytetrahydro-2-furancarboxylic acid is shown in Table 1.

TABLE 1 Concentration in enzymatic Activity inhibition rate reactionsystem (μg/ml) (%) 0.5 8.1 5 34.8 50 81.6 500 96.3

The concentration in enzymatic reaction system in Table 1 means theconcentration of 2,5-dihydroxytetrahydro-2-furancarboxylic acid in theenzymatic reaction system as described above. The concentration of2,5-dihydroxytetrahydro-2-furancarboxylic acid in the enzymatic reactionmixture that results in the activity inhibition rate of 50% (IC₅₀) ascalculated based on the concentration in enzymatic reaction system andthe AR activity inhibition rate was about 10.8 μg/ml.

Next, 2,5-dihydroxytetrahydro-2-furancarboxylic acid was added to an ADHreaction system to determine the ADH inhibitory activity.

A commercially available lyophilized product (Nacalai Tesque, code012-83) was dissolved in water for use as ADH. NAD (Nacalai Tesque) as ahydrogen donor and ethanol (Nacalai Tesque) as a substrate for theenzyme were used.

The ADH activity was measured as follows.

50 μl of water, 20 μl of 3 mM aqueous NAD solution and 10 μl of enzymesolution were added to 100 μl of 200 mM phosphate buffer (pH 6.2). 10 μlof sterile pure water was further added to the mixture. After 10 μl of60% ethanol was added thereto, the change in absorbance at 340 nm wasmonitored at room temperature for 3 minutes. The enzymatic activity wasdetermined on the basis of the change in absorbance per minute.

Next, aqueous solution of 2,5-dihydroxytetrahydro-2-furancarboxylic acidat a final concentration of 10.8 μg/ml and sterile pure water were addedto the reaction system as described above in place of 10 μl of sterilepure water. The enzymatic activity was then determined as describedabove. The ADH enzymatic activity inhibition rate was calculatedaccording to the above-mentioned equation based on the enzymaticactivity.

The ADH activity inhibition rate of2,5-dihydroxytetrahydro-2-furancarboxylic acid at IC₅ for AR activitywas 7.1%, indicating that the AR inhibitory activity of the compound ishighly selective.

In addition, other derivatives had equivalent activities.

EXAMPLE 2 Injectable Preparation

(1) 0.1% solution of 2,5-dihydroxytetrahydro-2-furancarboxylic acid ininjectable distilled water was prepared and sterilized by filtration toprepare an injectable preparation.

(2) 1% solution of 2,5-dihydroxytetrahydro-2-furancarboxylic acid ininjectable distilled water was prepared. An aliquot of the solutioncorresponding to 10 mg of dry material was dispensed into a vial forlyophilization, and then lyophilized. 2 ml of saline was separatelyattached thereto for dissolution.

EXAMPLE 3 Tablet

Tables were formulated as follows.

2,5-Dihydroxytetrahydro-2-furancarboxylic acid 10 mg Cornstarch 65 mgCarboxymethylcellulose 20 mg Polyvinylpyrrolidone  3 mg Magnesiumstearate  2 mg Total weight in a tablet 100 mg 

As described above, the present invention provides a pharmaceuticalcomposition effective for preventing and/or treating a disease due to ARactivity such as diabetic complications including cataract, peripheralneuropathy, retinopathy and nephropathy, which has a highly selectivephysiological AR inhibitory activity and which is highly safe for aliving body, or a composition for inhibiting AR.

What is claimed is:
 1. A method for treating a disease due to an aldosereductase activity or a disease complication of said disease, whichcomprises administering at least one compound having an aldose reductaseinhibitory activity selected from the group consisting of2,5-dihydroxytetrahydro-2-furancarboxylic acid of formula 1:

as well as derivatives, optical isomers and pharmacologically acceptablesalts thereof, wherein said derivatives are selected from the groupconsisting of compounds of formula 2:

wherein R¹, R² and R³ may be the same of may be different from eachother, and are hydrogen, an aliphatic group, an aromatic group or anaromatic aliphatic group; m and n are 1 or 0, provided that in case ofm=n=0, R¹, R² and R³ are not simultaneously hydrogen.
 2. The methodaccording to claim 1, wherein said disease complication is a diabeticcomplication due to the aldose reductase activity.
 3. The methodaccording to claim 1, wherein the diabetic complication is cataract,peripheral neuropathy, retinopathy and/or nephropathy due to the aldosereductase activity.
 4. A method for inhibiting aldose reductase, whichcomprises inhibiting aldose reductase using at least one compound havingan aldose reductase inhibitory activity selected from the groupconsisting of 2,5-dihydroxytetrahydro-2-furancarboxylic acid of formula1:

as well as derivatives, optical isomers and salts thereof, wherein saidderivatives are selected from the group consisting of compounds offormula 2:

wherein R¹, R² and R³ may be the same or may be different each other,and are hydrogen, an aliphatic group, an aromatic group or an aromaticaliphatic group; m and n are 1 or 0, provided that in case of m=n=0, R¹,R² and R³ are not simultaneously hydrogen.